Fuel tank

[Bob Kane]

In my case, the engine (YS140FZ) would quit because the fuel line inside the tank was pinched when the clunk would flop to the front of the tank during downlines and stay there. The gentle pull back to level flight was not enough force to pull the clunk to the back of the tank. Not every time, but during a contest even once is too many. I should add this was a Tetra standard tank. They are supplied with a thin-walled silicone tube, much more flexable than regular fuel line. To keep the fuel line from getting folded, I assemble the pickup line with a 3" (approx) 1/8" aluminum tube in the center. So, starting at the short tube through the stopper, I put a short piece of silicone tubing, then the 3" aluminum tube, then another short piece of silicone tube, then the clunk. The metal pieces should not touch each other.  I have never had the engine quit because the clunk was out of the fuel for the duration of a downline. For fun I sometimes climb nearly out of sight, then let the plane fall with the engine at idle and pull out low to the ground. The plane makes a nice  whooshing sound. The engine has never quit during one of these extended downlines. This is looking like a K-Factor article with pictures. monds <alan at gspceilings.com> wrote:Good Thread!  But which is right?   Stop the clunk falling to the front of the tank and potentially crimping the fuel lineorUse a thin walled line that will always fall to the front of the tank. Does it make any difference with the engine ticking over? I use the thin walled tube myself but would be interested to know which camp is the majority. Alan Simmonds-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org] On Behalf Of Bob Kane
Sent: 29 April 2003 04:56
To: discussion at nsrca.org
Subject: Re: Fuel tank

Does it quit on the way up, or on the way down?  What kind of engine are you using?  There are at least two possible problems. Your idle setup could be off, causing the changing fuel flow during this manuever to kill the engine. The engine should run for a long time at idle with the fuel remaining in the line even when the clunk is "high and dry" so to speak, certainly long enough to finish the downline and level off, restoring fuel flow. The other problem could be a pinched fuel line inside the tank. I had similar problem, flameouts after a stall turn. I discovered the clunk would pull the feeder line into the fuel on a downline but the clunk would stay in the front of the tank, folding the feeder line and starving the engine of fuel. I now assemble my tanks with an aluminum tube in the pickup line so the clunk can't fold back on itself. I would make sure the idle setup on your engine is reliable. It should idle for a very long time with no change in rpm.  Run the engine on the ground at full throttle, then pull back to idle. If it runs at steady rpm, all is fine. If it slowly slows down and dies, it is rich. If is speeds up then dies, it is lean.

Jerry Wilson <jerrywil at swbell.net> wrote:I have just found a problem that I'm sure many people on the list have solved before.  Often while doing a stall turn, my engine would stop and a dead stick landing would follow.  After discussing this with a friend at the field it was suggested that it could be a fuel tank problem.  So I took the tank out tonight to have a look.  With fuel inside I could see that when the tank was inverted as in a stall turn manouver as you go over the top,  the clunk would often rest against the side of the tank.  So when the nose is pointed down, the clunk could hang at the aft end of the tank but the fuel is at the nose.  I've changed the length of the tubing (shorter and longer) and even added a wheel collar to the line at the clunk, but so far I can't tell much difference. Any suggestions would be appreciated, thanks,Jerry 

Bob Kane
getterflash at yahoo.com 

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Bob Kane
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